Suspensions are

Which one of the following is a hydrophilic colloidal sol?

Which of the following colloidal solutions cannot be prepared by Bredig's arc method?

Sodium lauryl sulphate is an example of:

In the following reaction for the preparation of gold sol,$a, b, c, x, y$ and $z$ are $a AuCl_3 + b HCHO + c H_2 O \longrightarrow x Au (\text{sol}) + y HCO_2 H + z HCl$. Find the correct values for the coefficients.

Which of the following reactions leads to the formation of a substance in the colloidal state (in the presence of excess of $HCl$)?